1 | // -*- c++ -*- |
---|
2 | #include <iostream> |
---|
3 | #include <fstream> |
---|
4 | |
---|
5 | #include <lemon/smart_graph.h> |
---|
6 | #include <lemon/list_graph.h> |
---|
7 | #include <lemon/dimacs.h> |
---|
8 | #include <lemon/time_measure.h> |
---|
9 | #include <lp_solver_wrapper_3.h> |
---|
10 | |
---|
11 | using std::cout; |
---|
12 | using std::endl; |
---|
13 | using namespace lemon; |
---|
14 | |
---|
15 | template<typename Edge, typename EdgeIndexMap> |
---|
16 | class PrimalMap { |
---|
17 | protected: |
---|
18 | LPGLPK* lp; |
---|
19 | EdgeIndexMap* edge_index_map; |
---|
20 | public: |
---|
21 | PrimalMap(LPGLPK& _lp, EdgeIndexMap& _edge_index_map) : |
---|
22 | lp(&_lp), edge_index_map(&_edge_index_map) { } |
---|
23 | double operator[](Edge e) const { |
---|
24 | return lp->getPrimal((*edge_index_map)[e]); |
---|
25 | } |
---|
26 | }; |
---|
27 | |
---|
28 | // Use a DIMACS max flow file as stdin. |
---|
29 | // max_flow_expresion < dimacs_max_flow_file |
---|
30 | |
---|
31 | int main(int, char **) { |
---|
32 | |
---|
33 | typedef ListGraph Graph; |
---|
34 | typedef Graph::Node Node; |
---|
35 | typedef Graph::Edge Edge; |
---|
36 | typedef Graph::EdgeIt EdgeIt; |
---|
37 | |
---|
38 | Graph g; |
---|
39 | |
---|
40 | Node s, t; |
---|
41 | Graph::EdgeMap<int> cap(g); |
---|
42 | readDimacs(std::cin, g, cap, s, t); |
---|
43 | Timer ts; |
---|
44 | |
---|
45 | typedef LPGLPK LPSolver; |
---|
46 | LPSolver lp; |
---|
47 | lp.setMaximize(); |
---|
48 | typedef LPSolver::ColIt ColIt; |
---|
49 | typedef LPSolver::RowIt RowIt; |
---|
50 | typedef Graph::EdgeMap<ColIt> EdgeIndexMap; |
---|
51 | EdgeIndexMap edge_index_map(g); |
---|
52 | PrimalMap<Edge, EdgeIndexMap> lp_flow(lp, edge_index_map); |
---|
53 | |
---|
54 | // capacity function |
---|
55 | for (Graph::EdgeIt e(g); e!=INVALID; ++e) { |
---|
56 | ColIt col_it=lp.addCol(); |
---|
57 | edge_index_map.set(e, col_it); |
---|
58 | if (cap[e]==0) |
---|
59 | lp.setColBounds(col_it, LPSolver::FIXED, 0, cap[e]); |
---|
60 | else |
---|
61 | lp.setColBounds(col_it, LPSolver::DOUBLE, 0, cap[e]); |
---|
62 | } |
---|
63 | |
---|
64 | for (Graph::NodeIt n(g); n!=INVALID; ++n) { |
---|
65 | LPSolver::Expression expr; |
---|
66 | for (Graph::OutEdgeIt e(g, n); e!=INVALID; ++e) |
---|
67 | expr+=edge_index_map[e]; |
---|
68 | for (Graph::InEdgeIt e(g, n); e!=INVALID; ++e) |
---|
69 | expr-=edge_index_map[e]; |
---|
70 | // cost function |
---|
71 | if (n==s) { |
---|
72 | lp.setObjCoeffs(expr); |
---|
73 | } |
---|
74 | // flow conservation |
---|
75 | if ((n!=s) && (n!=t)) { |
---|
76 | RowIt row_it=lp.addRow(); |
---|
77 | lp.setRowCoeffs(row_it, expr); |
---|
78 | lp.setRowBounds(row_it, LPSolver::FIXED, 0.0, 0.0); |
---|
79 | } |
---|
80 | } |
---|
81 | lp.solveSimplex(); |
---|
82 | //std::cout << lp.colNum() << std::endl; |
---|
83 | //std::cout << lp.rowNum() << std::endl; |
---|
84 | //std::cout << "flow value: "<< lp.getObjVal() << std::endl; |
---|
85 | for (Graph::EdgeIt e(g); e!=INVALID; ++e) |
---|
86 | flow.set(e, lp_flow[e]); |
---|
87 | } |
---|